DIFFERENCES BETWEEN AS-2 AND AS-4 IN THE HOMOEPITAXIAL GROWTH OF GAAS(110) BY MOLECULAR-BEAM EPITAXY

The homoepitaxial growth of GaAs(110) thin films by molecular beam epi taxy has been studied in situ by reflection high-energy diffraction. R HEED specular beam intensity oscillations were recorded over a wide ra nge of growth conditions in which the substrate temperature, growth ra te, V/III flux ratio and the relative amount of As-2 or As-4 in the in cident arsenic beam were varied. These conditions were plotted to prod uce a phase map of the growth conditions for which specular intensity oscillations were recordable. RHEED oscillations were obtained over a much wider range of growth conditions when using As-2 compared to grow th using As-4. It is shown that this is related to the very different incorporation coefficients of the two arsenic species and reflects the requirement of a high arsenic adatom concentration in order to mainta in the 1:1 stoichiometry of the nonpolar (110) surface. (C) 1995 Ameri can Institute of Physics.